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|Year : 2013 | Volume
| Issue : 1 | Page : 1--2
Challenges to pneumococcal vaccine in India
Head of Clinical Microbiology, Pondicherry Institute of Medical Sciences, Puducherry, India
Head of Clinical Microbiology, Pondicherry Institute of Medical Sciences, Puducherry
|How to cite this article:|
Kanungo R. Challenges to pneumococcal vaccine in India.Indian J Med Microbiol 2013;31:1-2
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Kanungo R. Challenges to pneumococcal vaccine in India. Indian J Med Microbiol [serial online] 2013 [cited 2020 Apr 3 ];31:1-2
Available from: http://www.ijmm.org/text.asp?2013/31/1/1/108701
Several countries have included pneumococcal vaccine in their childhood immunization program for almost a decade now. Recently Pakistan has introduced the vaccine while vaccine coverage has been expanded to more countries within Africa. India has not yet taken up routine pneumococcal vaccination in the primary immunization program of infants and children. Prevention of invasive infections due to Streptococcus pneumoniae among children in India has been a challenge. Reports of high disease burden of pneumococcal pneumonia and other invasive diseases among children less than five years in India have been estimated by international bodies. WHO estimates 0.7-1 million deaths among children under five years of age attributed to pneumococcal diseases in the developing world.  Deaths in India are estimated to be around 141,000. Some reports of invasive pneumococcal disease have been published from multicentric studies by Invasive Bacterial Infection Surveillance (IBIS) Group, International Clinical Epidemiology Network (INCLEN)  (South Asian Pneumococcal Alliance, (SAPNA) and Asian Strategic Alliance for Pneumococcal disease prevention (ASAP).  An editorial in Indian Paediatrics by Levine and Cherian (2007) mentions the burden of pneumococcal disease to have remained undiminished in India.  Most reports on disease burden are through observational studies and are not supported by culture and laboratory data. A review published in Vaccine in 2009 highlights the lack of large, sustained long duration studies to estimate the incidence of actual disease burden.  In India, the exact burden due to invasive pneumococcal disease in children is not known. Recently, there was a news item that a large scale surveillance of pneumococcal disease is being launched by the pharmaceutical company GSK.  It will be interesting to see the methodology adopted in this study to capture the actual data of pneumococcal disease.
Serotype prevalence and antibiotic resistance in invasive pneumococcal disease (IPD) have been documented in some multicentric studies in India. ,, Isolated reports from single site studies have also been published. However, most of these studies have been carried out a decade ago. There is lack of current data from India to show change in the serotype prevalence over time. In this background, introduction of pneumococcal vaccine in the immunization schedule poses few challenges. Estimation of disease burden of pneumonia in children is done based on clinical data. However, actual estimation of the disease, based on laboratory evidence, is more challenging. Pitfalls in laboratory confirmation of pneumococcal pneumonia are well understood. Some of the greatest challenges to isolation of S. pneumoniae in the laboratory are inappropriate sampling, prior antibiotic treatment and lack of standard media. The other important and perhaps the most difficult step in documenting serotype prevalence is the lack of typing facilities in almost all laboratories, except a few within the country. High cost of the anti-serum is a major deterrent to routine serotyping of strains by clinical laboratories. Molecular methods for typing are again limited to very few centres.
To introduce polyvalent capsular polysaccharide pneumococcal vaccine (CPV), and conjugate vaccine in India, there is a need to address these issues. A concerted effort is required to carry out surveillance of disease burden taking into account correct sampling, which is geographically and demographically representative. WHO recommends appropriate surveillance to measure disease burden and collect a base line data.
The surveillance team at every site must include paediatricians/physicians who are the first point of contact in the hospital, besides microbiologists. The investigators have to be sensitized to the need for laboratory support. Laboratory must have the capacity to screen and detect pneumococcal isolates and carry out susceptibility testing by standard operating procedure common to all sites. However, serotyping of the isolates would form a major hurdle. As mentioned earlier, a few sites which have the capacity for serotyping would have to be included in the study to do this. Timely analysis and dissemination of results is crucial for the impact of the study on policy decisions. The dynamics of the disease changes with changing demography, treatment modalities and other confounding factors in the epidemiology of pneumococcal disease. Isolated reports of serotype prevalence within the country have not had any impact on the actual knowledge on status of serotypes involved in pneumococcal disease among children in India. There is a need to fill this knowledge gap.
In addition to the paucity of data on disease burden and serotype prevalence, there are few other factors that need exploring.
Would the non-vaccine serotypes replace the vaccine types (as has been noted with HiB vaccine)? Replacement disease by non-vaccine serotypes have been documented in surveillance studies following widespread use of pneumococcal vaccine.  Impact of vaccination and replacement disease by non-vaccine serotypes needs to be monitored closely.Would the current antibiotic susceptibility pattern change in the non-vaccine serotypes? PCR in culture-negative pneumococcal empyema due to prior antibiotic treatment has clearly established the role of non-vaccine type in the aetiology Limitations of the conjugate vaccine need to be overcome by exploring other virulence factors that may have potential advantages. Specific capsular serotypes are responsible for pneumococcal disease and influence the outcome. One of the major limitations of the current polysaccharide vaccine is their inability to protect against non-vaccine serotype infections. This warrants the development of alternatives that may protect against pneumococcal disease across all serotypes. Pernille Martens et al. suggest 'that the virulence of pneumococcal serotypes should be considered in the design of novel vaccines'.A review on vaccine impact on pneumococcal disease by Keith P. Klugman  highlights several pertinent issues, which are: a) Role of children in transmitting infections to the adult vulnerable population, especially those with HIV. b) Nasopharynx as a niche for carriage of multiple serotypes as documented by post-5-PCV program in Gambia and 9-PCV in Sweto, South Africa.  c) Anti-microbial resistance in the persistence of infection and serotype distribution of pneumococci. Increase in serotype 19A, which is a drug-resistant strain in invasive disease, has led to the speculation that selection pressure of antibiotics and vaccination has led to the emergence of antibiotic-resistant non-vaccine serotypes. On the positive side of the vaccine is the reduction of secondary bacterial pneumonia in children with viral pneumonia following introduction of PCV. Speculation that S.pneumoniae may have a role in acute episodes of pneumonia in children with tuberculosis who get admitted to hospitals also needs to be studied. Pneumococcal vaccines, which have proved to be beneficial in the developed countries, need further studies to prove its efficacy in the developing countries by incorporating prevalent serotypes. This is reiterated in the recommendations of the Indian Academy of Paediatrics Committee on Immunization (IAPCOI) in Consensus Recommendations on Immunization and IAP Immunization Timetable 2012.  In the backdrop of scarcity of data on disease burden and serotype prevalence, the committee recommends a real time multisite surveillance network in the country. There is also a need to look at other virulence factors, which may be potential targets for vaccines to overcome the drawbacks of the current type specific capsular polysaccharides.
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